This invention relates generally to the generation of microwave energy, and more particularly to high power generation by charge bunching of an intense, current-modulated electron beam.
Charge bunching of a continuous electron beam is a technique already well known in the art, as disclosed for example in U.S. Pat. No. 2,813,996 to Chodorow. Such bunching technique, exploiting the high self-electric field property of an intense relativistic electron beam propagated through a buncher cavity of a Klystron amplifier device, has been utilized for generation of microwave energy with much success. A Klystron device is disclosed for example in U.S. Pat. No. 4,049,995.
In a conventional Klystron amplifier, an electron beam is modulated by an electromagnetic field induced within a buncher cavity. For effective high power microwave generation, the Klystron amplifier is driven by an external microwave source while an intense relativistic electron beam is propagated through a drift tube into the buncher cavity thereby exploiting the high self-electric field property of such beam to enhance bunching and prevent RF breakdown under high voltage gaps. Because of the self-electric field, a space-charge threshold is imposed on current modification of a high current electron beam to somewhat limit operation of the Klystron amplifier as a high power microwave generator. It is therefore an important object of the present invention to increase the effectiveness of a Klystron device as a high power microwave generator by avoiding the space-charge current limitation and eliminating use of an external high power microwave source.